Almost every instance where we have on-premises 3CX there are dual internet connections. Most of the time both connections have static IP addresses and all traffic goes over the primary connection unless it fails; then everything goes over the secondary connection. We typically set this up in 3CX as dynamic IP's and set the STUN query interval down to like one minute. Unfortunately every time we call in for support they tell us this is an unsupported configuration and that dynamic IP should only be used for testing. I'd like to see a better way of handling dual internet connections.